Biologically active polypeptides or proteins which are attached to insoluble carrier materials, such as polymeric particles, are used in a variety of ways. For example, the diagnosis of pathological or other conditions in human beings and animals is often carried out using immunological principles for the detection of an immunologically reactive species, for example antibodies or an antigen, in the body fluids of persons or animals. An antigen is a foreign substance, such as a drug, hapten, toxin, lectin, polypeptide or protein which, when introduced into the body, causes the production of antibodies.
Other proteins and amine-containing compounds, such as enzymes, avidin, biotin or polysaccarides, have been covalently linked to various carrier materials for use in affinity chromatography, enzymatic reactions, specific binding reactions and immunoassays.
Carboxylated latex particles are used to prepare diagnostic reagents (U.S. Pat. No. 4,181,636). The conventional procedure for covalently attaching an immunologically reactive species to the particles having surface carboxyl groups involves the use of a water-soluble carbodiimide.